Television apparatus



Jan. 2, 1945. ANDERSON 2,366,307

TELEVISION APPARATUS Filed Oct. 29. 1942 All.

ATTORNEY ranged upon the luminescent target.

Patented Jan. 2, 1945 TELEVISION APPARATUS Earl I. Anderson,Manhassct, N. Y., assignor to America, a corporation of I Radio Corporation of Delaware ApplicatinnOctobcr 29, 1942, Serial No. 463,732

3 Claims.

l to provide for this form of synchronization, it is usually desirable to have the oscillator which controls the deflection of the cathode ray beam set to operate at a frequency relatively close to that of the received signalling impulses representing the time of completion (or in some cases the beginning) of the line, the field and the frame synchronization. I

Such apparatus usually comprises, in thereceiver instrumentality, a cathode .ray image reproducing tube in which a cathode ray beam is to produce or trace a raster developed and .ar- The television image is caused to appear on the raster traced by virtue of the cathode ray beam being signa1 modulated so that the image is built up point for point. To produce these effects the cathode ray beam which is produced is deflected under the influence of a suitable deflecting field which, in turn, is controlled by a deflection oscillator.

While, as above stated, it is customary to provide the absolute interlock of such deflection oscillators with the transmitter by virtue of received signalling energy, it is also customary to adjust the speed or rate 'of deflection to a value substantially coinciding with the rate at which the synchronizing signals are fed, and then the synchronizing signals are better able to take hold to control the image reproducing arrangement.

In many such forms of television apparatus it has been found to be especially convenient to provide separate chassis for the image reproducing .devices proper, which would comprise, generally speaking, both the Video and the audio equipment, and another chassis which would comprise, generally speaking, the deflection and power equipment.

It is usually desirable, in such arrangements, to providethe necessary control knobs or elements on the video and audio chassis, but nevertheless to arrange the deflecting oscillators and the like in the chassis with the image reproducing tube proper. However, to make this provision, difficulties are frequently encountered because of the development of high alternating current voltages of considerable magnitude which exist at various points of the system relative to ground.

Accordingly. it becomes one of the objects of this invention to provide an arrangement whereby the speed of an oscillator may be readily adjusted by way of a remote control without causing any interaction between any parts of the system.

Other objects of the invention are those of providing an improved manner of controlling the speed of oscillators by which the fidelity of picture reproduction in television apparatus is improved.

Other objects of the invention are those of providing a simplified arrangement for controlling oscillators and the like for controlling the deflection of cathode ray beams and, at the same time, providing controls which require very little adjusting and servicing.

The arrangement has been disclosed in one of its preferred forms by way =01 the accompanying drawing which illustrates one form .of the invention as applied to a speed control of the type generally known in the art as the blocking oscillator.

Referring now to the drawing, there has been provided an arrangement whereby television synchronizing signals are received and applied to the input terminal point 21 and fed by Way of the coupling condenser across theresis tor 25, which has one terminal connected to ground, and thence through one winding .29 of a transformer to the control electrode 3| of a relaxation oscillation system, such as that represented .by the blocking oscillator tube '33 of which the condenser 35 is provided with a charge in well known manner. Generally speaking, the tube 33 is connected to form what is known as a blocking oscillator and which has been set forth .and disclosed more fully in the patent granted to Tolson, Reissue No. 20,338, of April 20, 19357. In this arrangement, the tube 33 hasits plate or anode electrode connected by way of :a second winding 31 of the transformer 38 to :a source of positive voltage connected with the terminal 39 and for which a suitable by-pass condenser M is provided to ground at '21. The control electrode is also provided with the usual leak resistor 45 and is connected to the control electrode 5| of the second half of the tube 33 byway of a conductor 49.

The first half of the tube '33, comprising the cathode 43, the control electrode 3| and the plate or anode 32 functions in the manner of the blocking oscillator hereinabove described and represented, for instance, by the aforesaid Tolson patent. The second half of the tube 33 comprising the control electrode 5|, the plate or anode 53 and the cathode 55 functions in the nature of a discharge tube in manner well known.

The output energy for the discharge tube section is supplied toa terminal point 51 by way of the coupling condenser 59 connected across the load resistor SI and storage condenser 58 and the potentiometer 63 which tends to vary the amplitude of the output signals. Positive potential for the plate or anode 53 is provided by connection to the terminal point 65 which is suitably bypassed to ground 27 by way of the by-pass condenser 61.

In the usual installations the resistor 45 conback between the anode and control electrode of the said second named thermionic means, a second storage element connected to the control electrode of the second thermionic means and one winding of the transformer to derive charging energy from the said feedback and normally to maintain the said second thermionic means blocked, an alternating current path comprising a leak resistance and a capacity element ,connected between the control electrode of the second thermionic means and a predetermined point i of fixed potential, a direct current connection benects to ground by way of a;.second variable resistor so that at the connection point 68 a relatively high potential relative to ground 21 is found to exist.

In the present arrangement there is provided," however, a connection by way of the capacitor connected to.ground at 21 and the other terminal connected to the high voltage terminal 40 at which positive voltage for the amplifier tubes of the video and audio chassis, which is assumed to be separated from the main deflection oscillator, is provided, it becomes apparent that the speed of the oscillator section of the tube 33 may be adjusted by varying the position of the contactor on the potentiometer. As the bias applied by way of the conductor 13 through the connection made by the potentiometer 15 through the contactor 1'! is increased or made more positive, it is apparent that the speed of the oscil lator will tend to increase, and as the bias is reduced by way of the connection 11 being moved more closely toward ground 21, it will be apparent that the speed of the oscillator is reduced; Further, by providing the adjustment of the oscillator speed separate from the oscillator tube proper, it is apparent that the eiTects of interaction between the video amplifier and the speed controlled oscillator is reduced to a minimum. Itis apparent that the specific circuit herein shown is subject ,to certain" modifications without departing from the spirit and scopeof the invention. For instance, the blocking oscillator and discharge tube sections may be completely separate one from the other by housing them in different envelopes. Other modifications also may be made within the reasonable interpretation of the invention as it is hereinafter claimed. Having described my invention, what I claim as new and desire to have protected by. Letters Patent is:

1. Television apparatus comprising: ener y storing means, a charging means for :charging the said storage means substantially linearly,

and thermionic means including at least a cathode, a control electrode and an anode so connected to the storage means as to discharge the stored charge at predetermined time intervals 70 corresponding to current flow periods of the said thermionic means so that a substantially sawtooth wave formation is developed across the storage means, a second thermionic mean having at least an anode, a cathode and a control electrode, a transformer connection providing feedtween the control electrode of the said second "thermionic means and the control electrode of 5f the first named thermionic means so that the said tubes operate substantially at like time periods, potentiometric means connected to apply a variable biasing potential to the control electrode of the said second named thermionic means thereby to control the periodicity of operation thereof, and an independent connection for applying control impulses upon the control elec-;

trode of the second named thermionic means to serve as auxiliary control voltages.

2. Television apparatus comprising energy storing means, a charging means for charging the said storage means substantially linearly, and thermionic means including at least a cathode, a control electrode and an anode so connected to the storage means as to discharge the stored charge at predetermined time intervals corresponding to current flow periods in the said thermionic means so that. a substantially saw:

. tooth wave formation is developed across the storage'means, a second thermionic means having at least an anode, a cathode and a control electrode, a transformer connection providing feedback between the anode and control electrode of the said second named thermionicmeans, a second storage element connected to the control electrode of the second thermionic means and one winding of the transformer to derive charg ing energy from the said feedback and normally to maintain the said second thermionic means blocked, an alternating current path comprising a leak resistance and a capacity element con nected between the control electrode of the sec-,- ond thermionic means and a predetermined point of fixed potential to control the operational cycle in accordance with the rate of charge dissipation on the second storage means, a direct current connection between the control electrode of the said second thermionic means. and the control .electrode of the first named thermionic means so that each of said tubes operates substantially simultaneously, and remotely located potentiometric means connected to apply a variable biasing potential to the control electrode of the said second named thermionic means.

3. Television apparatus comprising energy storing means, a charging means for chargin the said storage means substantially linearly, and

thermionic means including at least a cathode, a control electrode and an anode so connected to the storage means as to discharge thestored charge at predetermined time interval corresponding to current flow periods in the said thermionic' means so that a substantially saw-tooth wave formation is developed across the storage age element connected to the control electrode of the second thermionic means and one winding of the transformer to derive charging energy from the said feedback and normally to maintain the said second thermionic means blocked, an alternating current path comprising a leak resistance and a capacity element connected between the control electrode of the second thermionic means and a predetermined point of fixed potential to control the operational cycle in accordance with the rate of charge dissipation on the second storage means, a direct current connection between 

